Pressure carburetor



INVENTOR,

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PRESSURE CARBURETO Filed Aug. so, 1946 l Nov. 7, 1950 Patented Nov. 7,1950 STATES' PATENT-Lf-oFFICE PRESSURE CARBURETOR Vandrewwilliam on,Jr., Detroit, Mich.. `assigner to George M. Holley and Earl HolleyApplication August 30, 1946, Serial No. 693,907v

(o1. zei-27) Claims.

The object of thisinvention is to supply fuel under pressure to aninternal combustion engine and to measure the quantity of fuel by thedepression in a venturi located in the air entrance. Specifically, thepressure of fuel delivered by an ordinary variable stroke diaphragm pumpin general use is caused to vary with the air flow as indicated by thedepression in the venturi in the air entrance. Fuel from this variablepressure variable stroke fuel pump is discharged directly into the inletmanifold without any float chamber.

The figure shows diagrammatically a formof my invention.

In the gure, III is the air entrance, I4 is the venturi in said airentrance, 22 is the throttle, which, when closed, places the opening 24below, that is, on the suction side of the throttle 22. This imposes asuction through pipe 28 in chamber I8. An adjustment 26 determines therelative effect of this suction which is most effective at closedthrottle (idling condition).

Air entrance pressure is admitted through the tube 96, past therestriction |00, to the chamber I8.

The pump 44-46-50-46-52-58-60 is adapted to deliver fuel at a pressuredetermined bythe air flow and by the pressure exerted by the spring 56.The pipe I6 connects to the chamber l2, above a diaphragm 13, and thechamber 14, below the diaphragm 13, is connected through the pipe 96 tothe air entrance I0. At the point of entrance 96 faces upstream.

The chamber 1I is also connected to the air entrance pressure throughthe pipe |02 which is connected to the pipe 96.

The fuel delivered from the pump ows through the restriction l0, atwhich point there is a drop which increases as the square of the flow.The pressure on the diaphragm 36 varies with the flow and the positionof the throttle 22, which varies the pressure in the air outlet 30,which varies the pressure in the chamber 34, to the left of thediaphragm 36.

The spring 62 tends to open the valve 40. The pressure in the airentrance is transmitted through the restriction IDU to the diaphragmchamber I8. The valve 66 is thus opened by the depression in the throatof the venturi I4, indirectly, because this depression causes the pumppressure in pump outlet 44 and in chamber |04, to the left of diaphragm68, to increase as the pressure in chamber 'I2 falls and imposes anincreased upward pressure on the diaphragm 54 of the fuel pump. Thevalve 66 thus opens in re- Y 2 sponse to an increase in the airowthrough the venturis I4 and 20.

The valve 40 opens in response to the opening of the throttle 22 whichincreases the pressure in the passage 30 through the passage 32 in thechamber 34. Spring 62 also assists in opening the valve 40 against thepressure in the chamber 38.

In this construction the fuel measured by the opening of the valve 66 isdelivered directly into the air passage 30 below the throttle 22.

Operation In the gure when operating with the throttle 22 closed down tothe dotted line (idle) position the restriction 24 imposes a slightsuction in the chamber I8 so that the valve 66 opens wide enough toadmit Aenough fuel so that the engine will idle. y

When the throttle 22 is opened to a normal running position. as shown infull lines, the valve 40 remains closed but the valve 66 progressivelyopens in response to an increase in suction in the venturi I 4 whichincreases the pressure difference across the diaphragm 'I3 which, actingon the diaphragm 54 increases the pump pressure acting in the passage44. This increase in pump fuel pressure in response to air iiow causesan increase in fuel ow to balance the increased air ow. The pressureacting on the spring 64 increases as the pressure acting on thediaphragm 54 increases.

At wide open throttle the valve 40 is opened automatically by the risein pressure in the passage 30, thereafter the fuel flowing past theannular passage around the stem of the valve 40 is added to the fuelflowing past the restriction 10.

What I claim is:

l. A fuel and air supply system for an internal.

combustion engine having an air entrance, a venturi therein, an airexit, a throttle valve therein, a variable pressure fuel pump whichincludes a moving wall acting as the pump piston. mechanical movingmeans having a one way connection with said wall on its suction strokeand a spring adapted to move said Wall on its pumping stroke so as todetermine the minimum pumping pressure means, means for increasing thepump pressure including means responsive to an increase in thedepression in the throat of said venturi, said means being adapted toact on said moving Wall so as to supplement the force exerted thereon bythe said spring, a fuel outlet, a valve in said outlet, a moving Wallconnected to said valve, an air chamber located on one side of said walland subjected to the pressure of the air entrance, yieldable meanstending to close said valve.

2. A device as set forth in claim 1 in which there is a restricted airpassage leading from the air exit below the venturi and so located thatit is on the engine side of the throttle only when the throttle issubstantially closed, a passage connecting this restricted opening tosaid air' chamber, a second restriction in the passage connecting saidair chamber to the air entrance whereby the pressure in the air chamberis temporariiy reduced when the throttle is substantially closed. l

3. A fuel and air supply'system for an internal combustion enginecomprising, an engine operated diaphragm pump, yieldable means formoving the diaphragm in the pumping direction, positive means for movingthe diaphragm in the suction direction, an air chamber, a seconddiaphragm connected to the first diaphragm and located so as to div'desaid chamber into two parts. an air entrance, a venturi therein, apassage subjectingone side o'f said second diaphragm to venturi suction,a second passage to the air entrance subjecting the other side of theair entrance pressure, the passages being connected to the air chamberassociated with the second diaphragm so that the second daphragm addsits influence to the yieldable means acting on the first diaphragm asthe venturi suction increases. a fuel entrance to the fuel pump, a checkvalve therein, a fuel exit, a check valve therein, a, fuel passageleading to an outlet into the main air passage, a valve in said outlet,a third diaphragm connected to said valve and responsive to the fuelpressure generated by said pump. yieldable means tending to close thevalve, an

4- air chamber on one side of said third diaphragm, a passage connectingthis aix' chamber to the air entrance.

4. A device as set forth in claim 3 in which there is a throttledownstream from said venturi and in which there is a restriction intheoutlet passage from said fuel pump, a bypass around said restriction,a valve in said bypass, means responsive to a rise in air pressuredownstream of said throttle to open said valve.

5. A device as set forth in claim 3 in which there is a throttledownstream from said venturi and in which there. is a restriction in thepassage connecting the air chamber associated with the third diaphragmto the air entrance, a restricted second passage connected to saidchamber leading to the air entrance at a point which is on the engineside of the throttle only when the throttle is almost closed so as tosupplement venturi suction during idling.

ANDREW WILLIAM ORR, Jn.

REFERENCES CITED The following references are of record in the

